Resinous copolymers of nuclearly polysubstituted isopropenyl benzenes



Patented July 14, 1953 rum-m STATES 1 RESINOUS COPOLYMERS on 1 d Q POLYSUBSTITUTED IsorRoPENY BEN- ZENES I l Theodore A; Te Grotenhuis-,"-lmstedFalls, and

Gilbert H. Swart, Akron, 0hio, a;ssignors to The .f i General ,Tire and Rubber Company, Akron, I

Ohio, a corporation of Ohio Application F b ry 23; 1950, Serial No. 145,992: s i 21 Claims (01. zed-80.7

No Drawing.

This application is a continuation-in-part of our copending application Serial No. 667,728,'fi1ed May 6, 1946, and the invention relates to'res'inous copolymerscomprising nuclearly polysu bstituted isopropenylben'zenes and to a method of D pa ing such copolymers. It particularly relates to thermoplastic resinous materials having high heat distortion and containing a plurality of nuclear substituents, at least one of which is a halogen, such aschlorine, fluorine, bromine, etc.

Inasmuch as'a main phase of the present invention deals with the outstanding results obtained bycopolymerizing two o f-the thirty nex't higher homologues' of "dichlorostyrene, -it' is thought that the present invention is clarified. by (1) I considering the defects or difficulties which have been encountered with the dichlorostyrenes, (2:) by comparing theipropertiesrelative to homopolymerization and copolymerization with monoolefines such as styrene of (a) the various isomeric dichlor'ostyrenes, (b) alpha-methylstyrene, and '(c)' the' thirty isomers of 'dichl'ord-alpha} methylstyrene (all of which are next higher homologues of dichlorostyrene). I

It is known that dichlorosty'ren es such asthe 1-vinyl-2, 4-dichlorobenzene and the l'-vinyl-2,5-' dichlorobenzene, and others may be polymerized and copolymerized to produce rubbers or resins having especially desirable properties. Thus, the rubbery copolymer of one or more butadiene compounds and a mixture of the isomers of dichlorostyrene has properties in several respects Superior to those of natural rubber for tire treads and the like. a 7

There are, for example, at least six isomeric dichlorostyrenes having the same empirical formula and having both-chlorine atoms on the bene zene ring. All six of these. isomeric dichloro styrenes homopolymerize, i. e, polymerize ,With themselves with extreme rapidity. In fact, they are so extremely active compared to styrene that great difiiculty is experienced in handling and preparing them. A substantial amountof inhibitor must be present during their preparation and storage and they should be stored atrelatively low temperature at all times prior touse. The result of this extreme activity toward polymerizae it has a CH3group in place of a hydrogen of the'dichlorostyren'e. It is recognized that there was a period in chemical history when it wascons'i'dered that a single member of a homologous se-y ries'indic'ated'the' properties of the higher members of the series. W hile' such may be true'of the simplesta'liphatic compounds, it is now reco v niz'ed that in more complex molecules the P D- ertiesof a lower homologue not only do'notneces sarilyindicate thepropertiesi of all next higher homologues' but may actually indicate false'and misleading properties. The'error of drawing conalso have properties similar to the dichlorostyrene itself.

tion renders their preparation and 'theprep rfi differs from that of dichlorostyrene only in that styrenes, two 'homologues of each, namely, those having methyl groups in the alpha orbeta posi tioh, are nojt lonlynot ashighly reactive toward hom opolyme'riaation as] are the dichlorostyrenes but have no appreciable or noticeable tendency to .hornopolymerizeby free radical mechanisms. Furthermoreldof these 12 next higher homologues of dichlorostyrene are apparently inertto cop'olymerizatmn by free radical mechanisms with the more. desirable resin forming mono:

olefinessuch.asvstyrene, etc, such as described herein..- a It was the stated opinion of. others who, prior to .the present invention, had investigated homo polymerization and copolymerization of dichloroalpha-methylstyrenes prepared by a process analogous to that used commercially for preparing dichlorostyrenes, that all 12 of these structurally closely related materials were inert to 00- polymerization with monp-olefines.

Most of the dichloro-alpha-methylstyrenes also have properties unlikef these of alpha-methyl- Alplia-methylstyrene, as is well known, copolymerizes with various materials including styrene and many other mono-olefines to produce desirable polymerization products. h inertl behaviorvof the dichloro-alpha-methlll: styrene ;-pre1 oarekzland tested for copolymerization withstyrene priorto the present invention indicated: that all ofthe dichloro-alpha-methylstyren'es also Jdifiered radically as to copolymerizability not 'only fromdichlorostyrene but from alpha-methy1styrene as well? A main phase of the presentinvention is based on the discovery that the two isomers of dichloroalphamethylstyrene having chlorine or substituents'onthe 3,4- or 3,5-positions act very differently from the majority ofdichloro-alpha-methylstyrenes inthat they-copolymerize with a certo the method commercially used for the prep-' aration of the dichlorostyrenes, i. e. by subjecting cumene '(in place of the ethyl benzene) successively to nuclear chlorination, to side-chain chlorination, and subsequent side-chain dehydrochlorination. Such polychloroalpha methylstyrenes consist largely of isomers having chlorine in the positions adjacent the unsaturated side-chain (alkenyl group) and it is possible that they are thereby so sterically hindered that copolymerization with mono-olefines is prevented. In any event, we have been unable to polymerize or copolymerize (by the free radical mechanism) these materials with polymerizable olefinic monomeric materials to obtain desirable products, even though catalysts normally considered as suitable for initiating emulsion and mass. polymerization at ordinary temperatures are present. That steric considerations may not be the explanation for the strange behavior of the many dichloro-alpha-methylstyrenes is indicated by our later surprising discovery that the two dichloro-alpha-methylstyrenes that do copolymerize with certain other mono-olefines also copolymerize with each other and with certain other alpha-methylstyrene derivatives.

The present invention is not limited to copolymers of 3,4- and 3,5-dichloro-alpha-methylstyrenes and styrene but is based on the broader discovery that a few of the many isomers of diand tri-substituted alpha-methylstyrenes, act very differently than do most isomers of these materials in that they form exceptionally useful resinous coplymers with certain polymerizable monovinyl compounds such as styrene, methyl methacrylate and the like, whereas other isomers do not polymerize or copolymerize at all with such monovinyl compounds and give indications that the polysubstituents in the nucleus have rendered the alkylenyl group inert. The nuclearly diand tri-substituted alpha-methylstyrenes, with which mono-olefinic compounds copolymerize to produce useful resins as hereinafter described, have the following general formula where X is selected from halogen, and methyl, Y and Z are selected from hydrogen, methyl and halogen, at least one of Y" and Z being selected from methyl, and halogen and preferably one of Y and Z being hydrogen.

the benzene ring. The other ortho-para directing groups, namely OI-I, --OR and --NR2, where R, is hydrogen or alkyl, etc. highly activate the benzene ring and accordingly are undesirable. Halogen and especially chlorine constitutes the preferred substituents.

These alpha-alkylstyrenes include the 3,4-disubstituted alpha-methylstyrenes in which the nuclear substituents are selected from chlorine and. methyl groups. These 3,4-disubstituted alpha-methylstyrenes include:

3,4-dichloro-alpha-methylstyrenes; 3, dimethyl-alpha-methylstyrenes; 3-chloro-4-methyl-alpha-methylstyrenes; 3-fiuoroit-methyl-alpha-methylstyrenes;

3 -bromo-4-methyl-alpha-methylstyrenes; 3-methyl-4-chloro-alpha-methylstyrenes; and 3 -methyl-4 -fluoro-alpha-methylstyrenes.

All of these alpha-methylstyrenes in contrast to those having substituents at either the 2- or 6-positions are found to form resinous materials The present invention is particularly directed with desirable properties by copolymerization with resin-forming or polymerizable mono-olefinic compounds having monomer reactivity for copolymerization (Q value) greater than that of vinylidene chloride and vinylchloride. Q value is defined in an article by Charles Price entitled Some relative monomer reactivity factors, Journal of Polymer Science, vol. III, No. 5, pages 772-775. However, the disubstituted alpha-methylstyrenes, in which at least one of the substituents is halogen having an atomic weight no larger than bromine such as chlorine, bromine and fluorine, are found to have substantial advantages over the 'alpha-methylstyrenes in which both of the nuclear substitutents are methyl groups, or substituted methyl groups as hereinafter pointed out. Similarly, the disubstituted alpha-methylstyrenes in which both of the substituents are small halogen atoms such as fiourine, chlorine and bromine (particularly chlorine) are found to have considerable advantage over those in which one or both of the substituents is a methyl group.

The compounds of the above general formula also include the 3,5-disubstituted alpha-methylstyrenes in which the nuclear substituents are selected from methyl, and halogen groups. These 3,5-disubstituted materials include:

3,5-dichloro-alpha-methylstyrenes; 3,5-difluoro-alpha-methylstyrenes; 3,5-dibromo-alpha-methylstyrenes; 3-chloro-5-methyl-alpha-methylstyrenes; and 3,5-dimethyl-alpha methylstyrenes.

While the above nuclear substituted alphamethylstyrenes in which only two substituents selected from chlorine and methyl groups are much preferred, and give polymers of excellent properties, it is also found that nuclear trisubstituted alpha-methylstyrenes also copolymerize with monoolefinic materials, as hereinafter qualified, to form resinous compositions, provided such trisubstituted alpha-methylstyrenes are devoid of substituents in the 2- and fi-positions. These trisubstituted alpha-methylstyrenes include:

3,4,5-trichloro-alpha-methylstyrenes; 3,4,5-tribromo-alpha-methylstyrenes;

3 methyl- 4,5-dichloro-alpha-methylstyrenes;

3 ,5-dimethyl-4- chloro-alpha-methylstyrenes 3,4-dimethyl-5-chloro-alpha-methylstyrenes; 4-methyl-3,5-dichloro alpha methylstyrenes;

and 3,4,5-trimethyl-alpha-methylstyrenes.

It will be noted that the above members of the above general formula substituted alpha-alkylstyrenes found to copolymerize by free radical mechanism with mono-olefinic compounds having a monomer reactivity for copolymerization greater than that of vinylidene chloride are all characterized by being free of substituents in the nuclear positions ortho to the iso-alkylenyl group (the isopropenyl group). In other words, in compounds the copolymerization of which the present invention is concerned, the atoms adjacent to the one carrying the isopropenyl group are free of all substituents, i. e. are connected to'hydrogen. We have been unable byany of the polymerization systems employing a free radical mechanism to copolymerize with any mono-olefinic compound a nuclearly disubstitutedalpha-methylstyrene having a substituent in the 2- and/or 6-positions on the nucleus. Neither emulsion nor the mass procedures were effective although the same procedures i. e. identical except for the different isomer of disubstituted alpha-methylstyrene were very effective for 3,4- and 3,5-disubstituted isomers.

The 3,4-dichloro-alpha-methylstyrenes may be prepared by any suitable process, as for example by alkylation of an ortho-dihalobenzene, such as ortho-dichlorobenzene, with a propylating agent such as propylene, isopropyl alcohol, and iso propyl chloride in the presence of aluminum chloride and subsequent dehydrogenation of the dichlorocumene. This is described in detail in the Guido H. Stempel, Jr. application Serial No. 778,747, filed October 9, 1947, and assigned to the assignee of the present invention.

The 3,5-dichloro-alpha-methylstyrene may be prepared as described in the aforementioned copending application of Guido H. Stempel from 3,5-dichlorobenzoic acid by treating it with thionylchloride to give 3,5 dichlorobenzoylchloride; reacting this product with methyl alcohol to form methyl 3,5-dichlorobenzoate; treating this ester with two equivalents of methyl magnesium chloride, hydrolyzing, and then dehydrating the resultant complex by refluxing it with sodium bisulfate. 3,5-dichloroisopropenylbenzene had a specific gravity of 1.196 and refractive index of 1.5660 both measured at C.

A preparation of 3-methyl-4-chloroisopro-- penylbenzene is also described in the aforementioned application of Guido H. Stempel. Briefly the process comprises subjecting 3-methyl-4- chloroacetophenone to 4-molar methyl magnesium chloride in ether, pouring the reacted mixture over cracked ice containing concentrated hydrochloric acid to form the corresponding carbinol, and dehydrating the carbinol by heating it in the presence of sodium bisulfate. The 3-methyl-4-chloroisopropenylbenzene had a boiling point of 107 to 108 C. at 17 mm.; a refractive index (D line) of 1.5519 at 25 C.; and a methyl alcohol and concentrated sulfuric acid;

then reacting this ester with 4-molar methyl magnesium bromide in ether; thereafter hydrolyzing the product with an ice-hydrochloric acid mixture to form the carbinol; and refluxing the carbinol with anhydrous potassium bisulfate. The 3 -chloro-4-methylisopropenylbenzene recovered by distillation boils at C. at 3 mm. It

' has a refractive index D line at 25 C. of 1.5508.

3,4-dimethyl-alpha-methylstyrene may be prepared as more particularly described in the pending application of Guido H. Stempel, Serial No. 145,590, filed of even date hereof and assigned to the assignee hereof. In accordance with the process 8,4-dimethyl-acetophenone which is first prepared from ortho-oxylene and acetic anhydride is heated with methyl magnesium bromide, the product hydrolyzed to the carbinol and the carbinol dehydrated. The BA-dimethyl-alphamethylstyrene boils at 86 C., freezes at 21 C. and has a refractive index No of 1.5376. 3,5- dimethyl-alpha-methylstyrene is prepared in a similar way starting with meta-xylene.

Halogenated alpha-alkylstyrenes and the other diand trisubstituted styrenes of the present invention as aforementioned for best results, such as highest heat distortion in the resinous copolymer, should be substantially free of alpha-alkylstyrenes having a substituent, such for example aschlorine, on the 2- and/or 6-positions of the nucleus. Such alpha-alkylstyrenes remain un-' polymerized in the product, and small amounts adversely affect properties desired for most applications. However, such unpolymerizable alphaalkylstyrenes may be present to remain as a plasticizer as they are usually compatible with the final resin. It is highly desirable that materials containing substituents in the 2- and 6-positions and other noncopolymerizablematerials do not exceed 25 per cent of the total amount of halogenated alpha-methylstyrenes as they are usually very difficult to remove from resinous copolymers.

Copolymerization with styrene and other polymerizable mono-olefines especially those con-' taining no oxygen and even homopolymerization of the 3,4- and 3,5-dichloro or disubstituted isopropenylbenzenes may be accomplished by the use of an ionic or acidic type catalyst such as those of the Friedel-Craftstype, say an aluminum chloride carbon disulfide or aluminum chloride methyl chlorine complex, or by boron fluoride or any of the usual boron trifiuoride complexes such as the boron trifluoride ether complex at low temperatures suchas below 40 C. and preferably below -80 C., employing techniques entirely analogous to those used for preparation of Butyl rubber. We have however, .been unable to effectively polymerize or copolymerize even with such powerful catalysts as the l-isopropenyl- 2-chlorobenzenes and others containing substituents on the 2- and/or 6-positions.

In accordance with the present invention, resinous compositions are made by interpolymerizing any one or more alpha-alkylstyrenes of the above mentioned general formula and preferably one having a plurality of halogen atoms in the nucleus, i. e. attached to carbon atoms of the aryl group, but which do not contain substituents on the carbon next adjacent to that nuclear carbon atom directly carrying the olefine group, with one or more other polymerizable unsaturated compounds containing in any one aliphatic portion thereof but one activated ethylenic linkage, i. e. one olefine C=C group (including vinyl groups CH2=CH and vinylidene groups.

activated for vinyl polymerization by at least one activating group, such for example as aryl, -COOR in which R is hydrogen, alkyl, aryl, substituted alkyl, an amide group CONR WhereR is hydrogen or alkyl etc., acid'anhydride and pyridyl groups. The activating group is attached directly to a free valence of an olefinic carbon to activate the double bond. The above compounds are preferably further characterized in that both of the free valences of a single carbon of the olefinic group are not simultaneously connected to electron-donor groups selected from aryl, alkyl, owalkyl and --OCOR groups and the compounds have no atoms other than C, H, N, Cl, Br and O in the molecule. Two such donor groups, on any one carbon of the olefinic group,

' appear to render copolymerization very difficult unless a monomer of a positive type, such for example as maleic anhydride, is also present with the polychloro alpha alkylstyrena Generally the olefinic carbon directly carrying an activating group is attached to hydrogen or methyl.

The preferred resinous compositions are prepared by subjecting to free radical polymerizing conditions en masse, in aqueous suspension or in emulsion a mixture of a polyhalogenated alpha-alkylstyrene having, as above set forth, the 2- and fi-positions free of substituents and one or more other compounds containing a single activated olefine group C C having not in excess of two and preferably not more than one of the four indicated free valences directly connected to the equivalent number of groups selected from CN, COOR (where R is hydrogen, alkyl or substituted a1kyl),amide, acid anhydride -o-o-o-) l t and aryl (including halogenated aryl), and preferably phenyl. merization with the aforedesignated nuclearly disubstituted isopropenylbenzenes are further characterized by having remaining free valences connected to hydrogen and/or alkyl (preferably hydrogen and methyl) and by having no single carbon of the olefine group simultaneously connected directly to both aryl and alkyl groups.

1 The vinyl compounds which copolymerize with the derivatives of alpha-methylstyrene within the above general formula, which have an activity for copolymerization greater than that of vinylidene chloride and which contain a single olefinic double bond in the structural formula CH=(IJA (where A is a radical more electron'egative than alkyl) include styrenei the ring halogenated and ring methylated styrenes having up to 4 groups selected from halogen and methyl groups solely on nuclear carbon atoms for example, each of the nuclearly mono-, diand trichlorinated styrenes such as ortho-chlorostyrene, para-chlorostyrene, 3,4-dichlorostyrene, 3,5-dichlorostyrene, 2,5dichlorostyrene, 3-methyl 4 chlorostyrene, para-methylstyrene, etc., acrylic acid, its esters and amides, acrylonitrile and vinyl'pyridine.

The vinylidene compounds which have an activity for copolymerization greater than thatof vinylidene chloride, which are found to copolymerize with the same aforesaid derivatives of alpha-methylstyrene have the structure CI-Iz:C' where at least one of the disconnected valences is connected to a radical more electronegative than alkyl. These compounds include meth- These compounds for copolyacrylic acid, its esters such as methyl methacrylate and higher methacrylates and its amides and its nitrile.

Other mono-olefinic compounds also suitable in forming resinous copolymers with the alphamethylstyrene derivatives of the above general formula include the alpha-beta unsaturated acids, their anhydrides and esters, including maleic' and fumaric acids, maleic and fumaric anhydrides and diethyl maleate, etc. and nitriles of chloracrylic acid.

Comonomers such as the allyl maleates, the vinylacetylene, bivinylbenzene, etc., having more than one active aliphatic olefinic group present to provide cross linking agents to obtain infusible and nonthermoplastic resins. Appreciable amounts are generally undesirable except where an in situ casting technique is used.

.A conjugated diene such as butadiene 1,3, isoprene, dimethylbutadiene chloroprene, dimethylbutadiene 1,3, piperylene and the like may also be presented to modify the characteristics of the resinous copolymerizable material. The amount of such conjugated diene desirable in resinous compositions should not ordinarily be in excess of per cent by weight of the poly merizable ingredients, although as much as 40 per cent may be present in some instances. Inasmuch as the alpha-methylstyrenes polyhalogenated in the nucleus are exceedingly difiicult to homopolymerize, these materials should ordinarily be present in an amount not greatly exceeding mol per cent of the entire polymerizable ma-- terials in the mixture to be polymerized unless one desires amounts in excess of 50 mol per cent to plasti-cize the resinous composition. Some of the excess above 50 mol per cent apparently and surprisingly enters into the copolymer. The comonomer mixture as polymerized should for best results ordinarily contain less than 75 mol per cent of the monomers even though excess is removed later.

. Even a relatively small amount, such as l to 10 per cent, of the halogenated alpha-alkylstyrenes imparts desirable noticeably improved properties to the polymerization product obtained by polymerizing the mixtures of the monomers. More than 10 per cent, up to 50 or mol per cent give the higher heat distortion copolymers and in most cases about 5O mol per cent gives optimum properties.

The polymerization may be carried out in aqueous emulsion or suspension or en masse with or Without the addition of a solvent or diluent and preferably with the aid of a suitable polymerization catalyst, i. e. those capable of forming free radicals, including organic peroxides. 'If polymerization en masse is used it is preferred to utilize a relatively lower temperature during the first part of the polymerization and a higher temperature at the end of the cycle. An inert a mosphere should be present over the surface of the polymerizable materials to exclude oxygen which acts as an inhibitor.

. Polymerization en masse or the so-called pearl or suspension polymerization, wherein the mixture of polymerizable materials With oxidizing catalyst or other fre radical initiator is simply agitated in Water or solution of a non-surface activeprotective colloid in a suitable pressure vessel at an ordinary-to-moderately elevated temperature, isordinarily preferred when a clear resin suitable as a molding powder is desired. In cases when a water-reactive material such as maleic anhydride is present as one of the monoinis, polymerization of the mixed monomers in the absence of water may be required. If a clear resin is not necessary, we prefer to utilize emulsion polymerization wherein the mixture of polymerizable materials is incorporated in an aqueous solution or suspension of a surface active emulsifying agent with or without a protective colloid,

and with or without the addition of pigments,

plasticizers and the like, for the reason that polymerization may be more rapidly and more conveniently carried out and physical properties of the resultant copolymer are superior- The emulsifying agents may be of the cationic (usually quaternary ammonium compounds) or anionic types. a

Examples of suitable emulsifying agents which may be used are set forth inthe lists of surfaceactive agents compiled by F. J. Van Antwerpen, published in Industrial and Engineering Chemistry, January 1939, pages 66 to 69, January 1941, pages 12 to 22, and January 1943, pages 126 to 130. The copolymerization in aqueous solution is greatly facilitated by conducting it in a stirred vessel completely filled with liquid sothat there is substantial absence of any vapor-liquid interface for reflux action to occur.

The speed of polymerization may be controlled by addition of suitable activators such as complex salts of cobalt, particularly alkali metal cobaltinitrites and alkali metal aquo hydroxylo nitrite cobaltiate in conjunction with mercaptan such as dodecyl mercaptan, as well as other activators for emulsion polymerization as described in the copending application of John C. Warner and Harry Seltz, Serial No. 687,954, filed August 2, 1946, assigned to the assignee hereof.

The finely divided resinous compositions of the present invention may be molded directly or they may be ground or mixed with a plasticizer and/or solvent (capable of combining therewith at elevated temperature) to form a slurry which may be used as a coating or molding composition, etc. and the thus coated material subjected to heat to cause coalescence of the solidparticles and compatibility with plasticizer and remaining solvent. The resin may for example, be ball mill ground in the presence of a plasticizer which is compatible at nondestructive elevated temperatures. preferably diluted with a solvent or thinner such as a drying oil, a hydrocarbon liquid such as kerosene, etc. and used as a coating or dipping composition. If a dispersing agent such as one or more water-insoluble soaps, long chain amines,

ink lengthener obtained from still bottom distion are generally characterized by having a substantially higher heat distortion than have polymers of styrene and copolymers of an identical composition except that the polysubstituted a1- pha-methylstyrene issubstituted. by styrene or other monoolefinic materials. The nuclear polyhalogenated alpha-methylstyrene copolymers of the present invention and especially those hav- '10 ing halogen such as chlorine in the 3- and 4-positions on the nucleus have another surprising and outstanding feature in that they are found to be resistant to the deteriorating effect of hydrocarbons such as gasoline.

Polystyrene and hydrocarbon copolymers of polystyrene with alpha-methylstyrene and many other styrene derivatives have the undesirable characteristics of rapidly deteriorating when contacted with hydrocarbon liquids, such as gasoline, lubricating oils or solvents. Even as little as may be contained in wax and other dressings with which they might come in contact often ,cause destruction. Then arealso susceptible to absorption of plasticizers such as may be present in vinyl resins and the like. This deterioration is so extensive that a polystyrene article, for example, when contacted for only a few minutes with hydrocarbons will develop cracks and crevices that may extend through the entire article and cause it to disintegrate or to have an unsightly appearance. This fact and the fact that it and most otherthermoplastic synthetic'resins have a very low A. S. T. M. heat distortion temperature so that articles of these materials cannot be boiled in water without destroying a molded article perhaps constitute the most serious drawbacks to general acceptance of these resins.

The copolymers of the polychlorinated alphamethylstyrene with styrene and other material have much improved hydrocarbon resistance. The copolymers of 3,4-dichloro-alpha-methylstyrene with styrene, for example are not destroyed by prolonged contact with hydrocarbons. The extreme resistance of the copolymers of 3,4- dichloro-alpha-methylstyrene and other alphamethylstyrenes containing halogens in the 3- and 4-positions maybe explained by study of the molecular structure of the copolymer with styrene.

In a model polymer molecule made to show equal moles of 3,4-dichloro-alpha-methylstyrene .and styrene, the 3- and 4-chlorines in the copolymer may be seen to be arranged in spiral like fashion that apparently will completely protect the molecule. Also even the 3,5dichloro-alpha-methylstyrene copolymer is less resistant to deterioration but is much superior of styrene polymers.

The following examples in which parts are by weight, illustrate the present invention:

Example 1 Parts Alpha-methyl 3,4-dichlorostyrene 10 Styrene 25 Mixture of isomers of dichlorostyrene 35 The above ingredients were allowed to stand for 24 hours at 60 C. in a closed tube. colorless resin of high strength and good electrical properties was produced.

A clear, hard,

- :When the amount of dichlorostyrene was increased to provide a 90: ratio of the monomers, other conditions remaining the same, a hard resin was also produced.

Example 3 The ingredients of Example'B were substituted by 50 parts of acrylonitrile, "50 parts of 3,4-dichloro-alpha-methylstyrene, and about 0.5 part of a catalyst (benzoyl peroxide); other conditions remained the same- A hard, paleyellow resin having high strength and good properties was also produced. The yellow coloration was apparently due to impurities in the acrylonitrile.

' Example 4 p Parts Maleic anhydride 49 3,4-dichloro-alphamethylstyrene 93.5 Benzoyl peroxide 0.5

The above ingredients were mixed together and substituted for the ingredients of Example 3,

other conditions remaining the same; a strong,

hard, clear resin was produced.

I Ewample 5 Parts Styrene a 50 3,4-dichloro-alpha-methylstyrene 50 Emulsifying agent (Dresinate 'No. 731

which is believed to be a sodium soap of hydrogenated rosin) 4.0 NaOI-I 0.1 Catalyst (cumene hydroperoxide) 0.3

-Water 1 200 The styrene and the i dichloro-alpha-methylstyrene were freshly distilled so as to be free from inhibitor. They were first mixed together with the addition of catalyst and thewhole emulsified into the alkaline solution of the emulsifying agent and incorporated into a closed polymerization vessel which was so proportioned that the emulsion completely'filled the vessel and there was a complete absence of vapor space above.

the emulsion. The vessel Was fitted with a'trap and stand pipe filled with aqueous liquid to maintain a slight pressure on the polymerizable I reduced to as little as'l or 2 per cent a thermoingredientsand act as a reservoir to insure the absence of vapor space after contraction of volume occurred as a result of polymerization. The vessel was maintained at C. with constant agitation until polymerization of the polymerizable ingredients was complete. The resultant latex was coagulated with 10 per cent acetic acid washed with water and the coagulum dried in an was first pelletized and then molded. into test bars utilizing injection molding technique and injection mold pressure of 10,000 .to 30,000 p. s. i. and injectionmold temperature of from 475 to -500 F. The resultant casting had the following properties: specific volume 25.6 cubic inches per pound; a specific gravity 1;.080; castings had ten- .silegstrength of 6,000 to 8,000 p. s. i.; flexural strength 9,500 to 12,000 p. s. i.; impact strength 0.3 to 0.4 foot pounds per inch of notch; hardness '(RockwellM) 110;.7A. S. T. M. heat distortion 120 C.; (ii-electric cons tant"(10 cycles) 0.0006; water absorption (24 hours) 0.01 per cent; an amber transparent color; and an absence of craz- -ingor cracking when contacted with aliphatic carbons such as a lubricating oil, gasoline and the like. I

When the 3,4-dichloro-alpha-methylstyrene 1s 'oven maintained at C.. The dried coagulum plastic'resin having properties somewhat superior to those of poylstyrene is still obtained.

Encamplefi An equal number of parts of methyl-methacrylate was substituted for the styrene in Example 5, other conditions remaining the same, the resultant dry polymer when molded had an A. S. T. M. heat distortion of over C., a high impact strength and a very high tensile and flexural strength indicating the resulting resin to have exceptionally desirable characteristics. Then only one half of the styrene in Example 5 was replaced by 25 parts of methacrylateother conditions remaining the same, an exceptionally desirable resin having a high heat distortion was also produced.

' Example 7 .The temperature was gradually raised until a temperature of C. was reached about 24 hours later. The resultant copolymer was crystal clear, had high hardness and was very tough.

Example 8 Parts Dinvinyl benzene (containing about 60 per cent ethylstyrene) 3,4-dichloro-alpha-methylstyrene 50 Benzoyl peroxide 0.5

A mixture of the ingredients was heated en masse at C. to form a hard resin.

Example 9 7 Parts 3,4-dichloro-alpha-methylstyrene about 50 'Di-isobutyl acrylamide about 50 .Benzoyl peroxide about 0.5

A mixture of the above ingredients was heated at 150 C. within an inert oxygen free atmosphere in contact therewith for about 24 hours to form a hard resin.

The unobviousness of the properties conferred on an organic compound having as complex a molecule as styrene by simply forming a next higher homologue is also illustrated by the efiect of adding a methyl group to para-chloro-alpha- "methylstyrene and to meta-chloro-alpha-methylstyrene. r

There are three possible isomers of parachloro alpha methylstyrene (4 chloroisopropenylbenzene) which would if the formerly held old idea concerning the next higher homologue,

"is about identical. The methyl group may be substituted on the number 2 or number 3 carbons of the ring or on the beta carbon of the isopropenyl group. Only when the methyl group is substi- "tuted in the 3-position does the resultant next higher homologue copolymerize with styrene and the other mono-olefines herein set forth.

'Similarlythere are five possible isomers of 3- chloro alpha methylstyrene (3 chloroisopro- 'penylbenzene) yet when the methyl group is added to anyof the 2-, 6- or beta positions the resultant next higher homologue of B-chloroisopropenylbenzene fails to copolymerize with monoolefines such as styrene methylmethacrylate, etc.

as herein set forth. .Whenit is substituted at the 3 "4- or 5-positions the product is found .to copolymerize with their same mono-olefines using the same procedure as before attempted except that the next higher homologue of para-chloro-alphamethylstyrene is different. A similar difference in properties is shown by the next higher homologues of para-methyl-alpha-methylstyrene.

The concept of an homologous series would indicate that all five of the isomeric next higher homologues of meta-chloro-alpha-methylstyrene and all of the isomeric next higher homologues of para-chloro and para-methyl-alpha-methyllstyrenes to be the same. These differences are illustrated by the following Examples and 10A hereof.

' Example 10 The 3,4-dichloro-alpha-methylstyrene of Ex- .ample 5 is substituted by an equal weight oi 3- chloro-4-methyl-alpha-methylstyrene, other conditions and ingredients remaining the same, the copolymer produced in about 100 per cent yield and has an A. S. T. M. heat distortion point of about 109? C. and has extremely good physical properties. When the 4-chloro-3-methyl-alphamethylstyrene is substituted for the 3,4-dichloroalpha methylstyrene in Example 5 a' resin having vdesirable properties is also obtained in good yield.

Example 10A The 3-chloro-4-methyl-alpha-methylstyrene of Example 10 is substituted successively by 2- 'methyl-3-chloro-6-methyl-3-chloro and the beta methyl-3-chloro, other conditions remaining the same. The resinous material which is obtained in each case in low. yield when analyzed fails to show any combined chlorine.

' The 3-chloro-4-methyl-alpha-methylstyrene of Example 10 is also successively substituted by an equal weight of 2-methyl-4-chloro and betamethyl 4 chloro alpha methyl styrene, other conditions remaining the same. The resinous material obtained in each of these cases in low yield also shows, when analyzed, no noticeable amount of combined chlorine. This conclusively shows that two of the three next higher .homologues of para-chloroalpha-methylstyrene, and three of the five next higher homologues of meta-chloro-alpha-methylstyrene do not form copolymers with styrene by theiree radical mechanism. When styrene in Example 10A is substituted by other mono-olefines, it is also found that copolymers are not formed.

The following examples further illustrate the present invention:

Example 11 i The styrene in Example 5 is substituted by 3,5- dichloro-alpha-methylstyrene, other conditions remaining substantially the same, except that the reaction is permitted to proceed for a longer time, the resinous copolymer obtained in good yield has an extremely high softening point. {The resinous copolymer is soluble in aromatic solvent mixtures and has, because of the extremely high softening point, exceptionally desirable properties for the preparation'of printing inks suitable for modern high speed presses. The copolymerization of these materials is indeed surprising as neither homopolymerized and it was assumed that the alpha-methyl group prevented two such molecules from getting together.

an equal weight of mixed isomers of dichlorostyrene, an excellent hard resin having outstanding properties is also produced.

Example 13 Parts 1 isopropenyl 3,4 dichlorobenzene 25 1 isopropenyl 4 chlorobenzene 2 5 1 vinyl 4.- chlorobenzene i 50 Benzoyl "peroxide 1 .alphamethylstyrene may be substituted inwhole or in part by any one or more 3,4- and 3,5- disubstituted alpha methylstyrenes as included in the aforementioned general formula. The styrene of Example 5 and/or comonomers in the above Example 5. and the methyl methacrylate in Example 6 may be substituted in whole or in part by any one or more ofthe mono-olefinic monomers previously mentioned as polymerizable with nuclear poly-substituted alpha-methylstyrenes. It is again emphasized that the 3,4- dichloro-alpha-methylstyrene and the 3,4-disubstituted alpha-methylstyrenes in general having halogen or especially chlorine in at leastone of the 3 or 4 positions produce copolymers having outstanding properties. While the corresponding bromine and iodine derivatives produce resins suitable for many commercial applications, products containing fluorine and chlorine in the nucleus are usually preferred. The catalysts, activators, etc., may be substituted for other free radical catalysts. The temperature of polymerization may be varied as is evident from those skilled in the art. When the olefinic group in the comonomer is activated by chlorine or by an acetate group such as is present in the vinylchlorine, and vinyl acetate, desirable copolymers are obtained when there is present a sufficient third monomer to copolymerize with the chlorine or acetate activated mono-olefine.

The following example is given to further illustrate the selective copolymerization of the 3,4- dichloro-alpha-methylstyrene. The 50 parts of 3,4 dichloro-alpha-methylstyrene were succesively mixed with 50 parts of each of the monomers shown in the following table and emulsified in parts of water containing 5 percent of soap (Na stearate) and 3 parts of sodium persulfate, the emulsion was treated as in Example 5 and the polymerization was carried out at 50 C. The materials were maintained in this temperature for two weeks. The yield, melting point, percentage of bound chlorine in the copolymer and the ratio of monomers in the final polymer as indicated by the percentage of chlorine is shown in the following table:

r Shows the percentage of monomers as calculated from bound chlorine in the copolymer.

The above shows that fact that there is something more than steric considerations that ren- 'der the homo-polymerization .of the alphamethylstyrene derivatives .unfeasible. It also illustrates the fact that there must be more than steric considerations that determine the copoly- .merizability of the various monomeric materials.

3,4-dichloro-a1pha methylstyrene may, as aforesaid, be rapidly homo-polymerized and copolymerized with styrene and isobutylene in wide ranges by bubbling boron fluoride or its ether complex thru solution of these monomers in cold liquid ethylene for example. a

As used herein, the term interpolymerization product of a polyhalogenated alpha-alkylstyrene having the nuclear carbon atoms adjacent that carrying the vinyl group free of chlorine designates copolymers, interpolymers and materials otherwise named, which may be obtained by polymerizing together such a polyhalongenated alpha-alkylstyrene and one or more of the monomers of other polymerizable materials, such as those aforementioned, and containing less than 45 percent (preferably less than 20 per cent) by weight of any conjugated diene.

Since after the formationof a copolymeriza tion product of a conjugated diene and one or more monomers, the conjugated diene is not present in the copolymer as a conjugated diene but rather as a unit of the following formula it may be considered improper to say that the rather than the formula o=o-o=o V l Similarly the residue of 3,4-dichloro-alphamethylstyrene has the probable chemical formula where the free valances are connected to other residues from polymerization of the same or other monomers. It is therefore seen that the term residue from polymerization of a monomer designates that portion of the monomer molecules in the polymer.

The terms an acrylonitrile and an acrylic acid are used in the generic sense to respectively designate both acrylic and methacrylic nitriles are both acrylic and methacrylic acids.

In the appended claims the term activity for copolymerization or monomer reactivity for copolymerization are considered to be the Q value set forth in the article of Charles Price entitled Some relative monomer reactivity factors and appearing in the Journal of Polymer Science, vol. 5, pages 772 to 775.

Although several embodiments of the invention have been herein shown and described, it

will be understood thatin accordance with the provisions of the patentstatutes modifications maybe made without departing from the spirit thereof and it is intended that the invention be limited only by the appended claims.

We claim:

l. A resinous interpolymerization product comprising in copolymerized form (1) at least one isopropenyl benzene of not in excess of ten carbon' atoms and consisting of carbon, hydrogen and chlorine, all of said chlorine being attached to a nuclear carbon atom, said isopropenyl benzene having only two substituents both of which are attached directly to nuclear carbons said isopropenyl benzene being further characterized by having both of the nuclear carbon atoms next adjacent that directly carrying the isopropenyl group connected to hydrogen and (2) at least one polymerizable mono-olefinic compound having no atoms other than C, H, N, Cl, Br and O in the molecule in which the olefinic group is directly connected to a radical more electronegative than alkyl, said radical being selected from the group consisting of CN, acid anhydride, aryl, amide pyridyl, and COOR groups where R is selected. from the group consisting of hydrogen, alkyl, and substituted alkyl, said interpolymerization product comprising not in excess of 25 per cent by weight thereof of a conjugated di-olefinic compound.

2. The interpolymerization product of claim 1 further characterized in that one of the carbon atoms of said olefinic group of said polymerizable mono-olefinic compound is connected to two hydrogen. atoms.

3. The interpolymer according to claim 1 in which both of said nuclear substituents in said alpha-methylstyrene are in the 3- and l-positions.

l. A resinous interpolymer according to claim 1 in which at least part of said isopropenyl benzene is 3,4-dichloro-alphamethylstyrene and where at least'part of the said polymerizable monoolefinic compound is styrene.

5. A resinous interpolymerization product of a liquid mixture comprising 3,4-dichloro-alphamethylstyrene and styrene, said interpolymerization comprising not in'excess of 25 per cent by weight of the residue from the copolymerization of a conjugated di-olefinic compound.

6. A resinous interpolymerization product comprising 3,4-dichloro-alpha-methylstyrene and methyl methacrylate.

7. A resinous interpolymerization product of a liquid mixture comprising 3,4-dichloro-alphamethylstyrene and an aryl vinyl compound, said interpolymerization comprising not in excess of 25 per cent by weight thereof of the residue from polymerization of a conjugated di-olefinic compound.

8. A resinous interpolymerization product of a liquid mixture comprising 3,4-dichloro-a1phamethylstyrene and an acrylonitrile.

9. A resinous interpolymerization product of a liquid comprising 3,4-dichloro-alpha-methylstyrene and an ester of an acrylic acid, said interpolymerization product comprising not in excess of 25 per cent by weight thereof of a conjugated di-olefinic compound in combined form.

10. An interpolymerization product of styrene and a polyhalogenated alpha-methylstyrene having the nuclear carbon atoms adjacent the carrying vinyl group connected to hydrogen, said styrene and said polyhalogenated alpha-methylstyrene constituting at least 60 per cent of the components,- and said polyhalogenated alphamethylstyrene forming about 1 to about 50 mol per cent of the total components of said product.

11. The process which comprises copolymerizing in aqueous emulsion-a 3,4-dichloro-alphamethylstyrene and a compound having no atoms other than C, H, N, Cl, Br and O in the molecule containing a single olefinic group of the general formula C=C and having at least one of the four free valences thereof directly connected to a member of the group consisting of aryl, acid anhydride, CN, amide, pyridyl and COOR groups in which R is selected from the group consisting of hydrogen, alkyl, aryl, and substituted alkyl, said compounds being further designated by having no single carbon atom of the olefinic group simultaneously connected directly to both aryl and alkyl groups, the residue of 3,4- dichloro-alpha-methylstyrene in said mixture being 1 to 50 mol per cent of the residues of all polymerizable monomers after the completion of the polymerization of polymerizable ingredients in said mixture.

12. The process of claim 11 wherein the polymerization is conducted in the presence of a continuous phase of aqueous liquid.

13. A resinous interpolymerization product comprising a nuclearly-dihalogenated alphaalkylarylvinyl compound having the nuclear carbon atom next adjacent that carrying the vinyl group connected to hydrogen, and a compound containing the group H2C=C and having one of the free valences connected to a --CN group and another free valence attached to a group selected from hydrogen and a lower alkyl, the residue from said nuclearly dihalogenated alpha-alkylarylvinyl compound being 1 to mol per cent of the total residues of monomers in said interpolymerization product.

14. A method of producing a resinous interpolymerization product which comprises mixing a dichloroalpha-methylstyrene having the carbon atoms next adjacent that carbon atom which directly carries the isopropenyl group connected to hydrogen, a polymerizable mono-olefinic compound having no atoms other than C, H, N, Cl, Br and O in the molecule and having one of the free valences of the group, C=C directly connected to a phenyl group and having the remaining valences connected to hydrogen, contacting the mixture thus formed with a free radical forming catalyst and allowing the mixture to thicken to the resinous state, the residue from said dichloroalpha-methylstyrene in said mixture being 1 to 50 mol percent of the residues of all polymerizable monomers in said mixture.

15. A method of producing a resinous interpolymerization product which comprises mixing with a, dichloroalpha-methylstyrene having the carbon atoms that are next adjacent the carbon atom which directly carries the isopropenyl group connected to hydrogen, a mono-olefinic compound having no atoms other than C, H, N, Cl, Br and O in the molecule and having one of the free valences of the olefinic group, C=C directly connected to a phenyl group and having the remaining valences connected to hydrogen, distributing the mixture thus formed through a continuous phase of water and maintaining the polymerizable ingredients in said water until they are transformed into the solid state, the residue from said dichloro-alpha-methylstyrene in said mixture being 1 to 50 mol per cent of the residues of all polymerizable monomers in said mixture.

16. Method of preparing a, resinous polymeriza- 13' tion product which comprises mixing (1) isopropenyl benzene having a plurality of substituents, allof which arein the nucleus and none of which are in the 2- and 6-positions, all of saidflsubstituents being nitrogen and oxygen free and being mono-valent ortho-para directing groups which have less than two carbon atoms which do not appreciably activate the benzene ring and which have less than two carbon atoms and have an atomic weight of less than 36, and (2) a polymerizable mono-olefinic compound having no atoms other than C, H, N, Cl, Br and O in the molecule and having attached directly to one 'of the carbon atoms of said olefinic group a non-halogen containing group more electronegative than allsyl, which non-halogen containing group is selected from the group consisting of aryl, acid anhydride, CN, amide, pyridyl andCOOR in which R is selected from the group consisting of alkyl, hydrogen, aryl, and substituted alkyl groups, subjecting said mixture to a suitable catalyst in the presence of a continuous phase or" aqueous liquid until a solid product is produced.

17. A resinous interpolymerization product comprising in copolymerized form (1) at least one isopropenyl benzene of not in excess of ten carbon atoms and consisting of carbon, hydrogen and chlorine, all of said chlorine being attached to a nuclear carbon atom, said isopropenyl benzene having only two substituents both of which are attached directly to nuclear carbons, said isopropenyl benzene being further characterized by having both of the nuclear carbon atoms next adjacent that directly carrying the isopropenyl group connected to hydrogen, and (2) at least one polymerizable mono-olefinic compound having no atoms other than C, H, N, Cl, Br and O in the molecule in which the olefinic group is directly connected to a radical more electronegative than alkyl, said radical being selected from the group consisting of CN, acid anhydride, aryl, amide pyridyl, and COOR groups where R is selected from the group consisting of hydrogen, alkyl, and substituted alkyl.

18. The method of preparing a resinous polymerization product which comprises reacting in the presence of a suitable catalyst (l) isopropenyl benzene of not in excess of ten carbon atoms and consisting of carbon, hydrogen and chlorine and having a plurality of substituents, all of which are in the nucleus and none of which are in the 2- and 6-positions, at least one of said substituents being chlorine, and (2) at least one polymerizable mono-olefinic compound having no atoms other than C, H, N, Cl, Br and O in the molecule in which the olefinic group is directly connected to a radical more electro-negative than alkyl, said radical being selected from the group consisting of CN, acid anhydride, aryl, amide pyridyl, and COOR groups where R is selected from the group consisting of hydrogen, alkyl and substitute alkyl, said interpolymerization product comprising not in excess of 25 per cent by weight thereof of a conjugated diolefinic compound and subjecting said mixture to a suitable catalyst until a solid product is produced.

19. The method of claim 18 in which the catalyst is a free radical forming catalyst and in which the mixture is incorporated into a continuous phase of water and is maintained in dispersed condition in said water until polymerization to a solid state occurs.

20. The method of claim 18 in which isopropenyl benzenes are present in a total amount mixture is free from more than 25 per cent of a conjugated diolefinic compound.

'21. A resinous interpolymerization product of a mixture comprising (1) an'isopropenyl benzene having a plurality of substituents, all of which are in the nucleus and none of which substituents are in the 2- or fi-positions, all of said substituents being nitrogen and oxygen free and being mono-valent ortho-para directing groups which have no more than one carbon atom and have a total atomic weight of less than 36 and (2) at least one polymerizable mono-olefinic compound having no atoms other than C, H, N, Cl, Br and O in the molecule in which the olefinic group is directly connected to a radical more electronegative thanalkyl, said radical being selected from the group consisting of CN, acid anhydride', 'a'ryl, amide pyridyl, and COOR groups THEODORE A. TE GROTENHUIS. GILBERT H. sWART.

References Cited in the file of this patent UNITED sTA'rEs PATENTS Number Name Date 2,406,319 Brooks et a1 Aug. 27, 1946 2,473,985 Brooks June 21, 1949 Te Grotenhuis et a1. Apr. 10, 1951 OTHER REFERENCES Bachman et al.: J. A. C. S., vol. 69, August 1947, pa es 0227- 025. 

1. A RESINOUS INTERPOLYMERIZATION PRODUCT COMPRISING IN COPOLYMERIZED FROM (1) AT LEAST ONE ISOPROPENYL BENZENE OF NOT IN EXCESS OF TEN CARBON ATOMS AND CONSISTING OF CARBON, HYDROGEN AND CHLORINE, ALL OF SAID CHLORINE BEING ATTACHED TO A NUCLEAR CARBON ATOM, SAID ISOPROPENYL BENZENE HAVING ONLY TWO SUBSTITUENTS BOTH OF WHICH ARE ATTACHED DIRECTLY TO NUCLEAR CARBONS SAID ISOPROPENYL BENZENE BEING FURTHER CHARACTERIZED BY HAVING BOTH OF THE NUCLEAR CARBONN ATOMS NEXT ADJACENT THAT DIRECTLY CARRYING THE ISOPROPENYL GROUP CONNECTED TO HYDROGEN AND (2) AT LEAST ONE POLYMERIZABLE MONO-OLEFINIC COMPOUND HAVING NO ATOMS OTHER THAN C, H, N, CL, BR AND O IN THE MOLECULE IN WHICH THE OLEFINIC GROUP IS DIRECTLY CONNECTED TO A RADICAL MORE ELECTRONEGATIVE THAN ALKYL, SAID RADICAL BEING SELECTED FROM THE GROUP CONSISTING OF-CN, ACID ANHYDRIDE, ARYL, AMIDE PYRIDYL, AND -COOR GROUPS WHERE "R" IS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, ALKYL, AND SUBSTITUTED ALKYL, SAID INTERPOLYMERIZATION PRODUCT COMPRISING NOT IN EXCESS OF 25 PER CENT BY WEIGHT THEREOF OF A CONJUGATED DI-OLEFINIC COMPOUND. 